Lock-stitch sewing machine



Sept. 20 1932. 1,877,757

M. HEMLEB LOCK STITCH SEWING MACHINE Filed Jan. 29. 1951r 4 sheets-sheet 1 es y :woe/"CM sept. zo, 1932. M, HEMLB 1,877,757

LOCK STITCHl SEWING MACHINE Filed Jah. 29.. 1951 4 sheets-sheet 2 Jl Q j o n Ji, f2' y j! u y Sept. 20, 1932. M. HEMLEB 'Locx STITCH SEWING MACHINE Filed Jan. 29, 1931 4 Sheets-Sheet 3 Mar'n Henzleb alom,

Sept. '20, 1932. M HEMLEB 1,877,757 I Loox STITCH SEWING MACHINE Filed Jan. 29, 1931 4 Sheets-Sheet 4 Van/zz Heinlein Patented sept. zo, 1932 Pasos OFFICE KEMER, QF=ELIZA BETE,`NEW JERSEY, ABSIGN'B T0 TE SINGER MANU- FCTUBING COMPANY, 0F ELIZABETH, NEW JERSEY, .t CORPORATION 0F NEW JERSEY I LOCK-STILE@ I EWING IAGEINE Application` medl'anuary 69.' 1831. 'Serial' No. [512.95m

, 'llfhfie invention relates to lock-stitch sewing machines of the type employing, a shuttle oscilla lin a vertical plane parallel tothe line on; eed.: Machines of this type have 5 been provided with reversiblefeeding mechgnisrhs of various kinds -for producing chieiy *seeking-utf .or back -itehing operations attire-ends ofstraightaway seams. It

. is known thatisuch a machine, when feeding 10' .the work' forwardly. or away; from the .operatar; ,.wi1l, make-.a Alock-stitch-infwhich' the needlethread spirals around the bobbinthreadeontinuously ini-the; same direction. VThis form of 'look-stitch is known tothe trade 15 asrthe perfect look-stitch. -f When the direetion. offeed is reversed, however, 'to make rbackcstitches7 v there isan Iabinnnlal` cooperationof the concerne'd elements whichf'resuits in a formi dflock-stitch'in 4which the needle im .thread makes a seriesoi knots .or half-bitches around thel bobbin-thread, fa't the same time iooseningthe strandsof the needle-thread and resulting in :imperfect lock-stitch or hitch-Stitchmf v lotwithstar'iding these known conditions and frequentEcomplaints of sewing machine.

users, no veffective remedy has been devised Aheretofore toharmonize a reversible feeding I'neehamsmI and the vtype 'of stitchforrning mechanism'referred to'. v

Th'ej present invention' has for :an Vob'ect to provide astraightaway" reversible'- eed shuttle-machine oithe type'r'eferred to, which s will sewiperfectlock-stitch seamsje'qually 5 well'ineitherdirection. lA:furtherobject 0f theinvention isto' 'attain the results aimed at; while retaining the Adesired direction of 'of theneedle and bobbirrthreads about b one-another, and without i terfering'with theI acceassibili'tjr 4 of f 'the bob 'in orv "renewal of thelbobbin-.threaxllfrriassr havefiond "by experimenting; "that Ai). shuttle machineI constructed ,with .a A"needle whichi threaded in a direction away from the bracket-armstxidard. and ashuttle oscillatingfin a, vertical plane'parallel to the line of feed and arranged to t'akethe needle-loop on the-,side ofthe'needle morejremote '.frfom 5b the standard, inay be causedto make a perfeet lock-stitch in harmony-with a reversible yclfear themo'de of 'operation of the present feeding mechanism while feeding the vvorlr forwardly or hscirwardiy in a line parallel to the plane oscillationof the slnrttle. This arr-:nn lement has not, so iar as am 'aware,`been eretorfore discovered and understood and put te f nseini purpose. l loef lQYe that I am the rst to harmonise a/relversible strai htaway feeding mechanism and a stitch-igtxrlningmechanism having a shuttle arranged to oscillate in a verticali. "de plane'parallel to the line of feed/and a. readily accessible bobbin, to sew Aperiect lockstitches of uniform twist `forwardly and bacia:- lwardly. l e

In theacccmpa'n lng drawings, Fig. l is a lon 'tudinal vertlcal section oil a sewing machine' embodying the invention. Fig. is an enlarged detail view of the needle. resserdoot and shuttle; the latter Abeing' in oop-seizinglposition. Fig. 3 is a vertical sec tion throu the bracket-arm standard on the 'line 234-3, ig. 1. Fig. 4 is anenlarged face view of the shuttle and 'shuttle race in position' below the sewing machine bed. Fig.. ii isl a lface'view of the stop-plate for the feed'-V reversing lever. Figs. 65,6" and @Gare diagrammatic perspective views illustrating in successive stages the formation of a'locir'- stitch by the presentmachine when adjusted to feed forwardly'or away from the operator., Figs. 7'?, Pand 7 aresimilar views illustrating .the formation of thestitch by the present machine when adj usted to feed rearwardly or I'toward the operator. Figs. 8, 8". 8 amig, 9", 9" are similar sets of views showing the stitchfformation of a lmown machine of the 'present 'type having reversible feeding mechanisrn. A comparative stud of these several sets of diagrammatic views will make mgrovement. n hegeneralfdonstructlve Vfeatures of the xfn'aclzrine will first be described.-v The frame comprises the usllfl bed 1 vfrom which rises the standard 2 ofthe 'bracket-arm 3 terminating in thehead 4 in which the needle-bar 5 carrying the eyeointed needle 6 is mounted to reciprocate. ournaled-"in the arm 3` is the main-shaft 7 carryingat its rearward end the'balance wheel 8 and at its forward end 16 the barrel-cam 9 for the usual take-up 10. The barrel-cam 9 has mounted on its end-face a crank-pin 11 which is connected by the link 12 tothe needle-bar 5. The head 4 also has mounted in it the spring-pressed presser-bar 13 carrying the usual presser-foot 14. The usual tension-device 15 is mounted on the face-plate 16 which closes the open face of the head 4.

The eedin mechanism is of the reversible type discl for example in the patents to Diehl No. 575,339, of Jan. 19, 1897, and Hleb No. 1,477,264, of Dec. 11, 1923. This medianism comprises a feed-advancing cam .17 fixed to the main-shaft 7 and embraced by the forked upper end of a pitman 18 the lower Iendof which is pivotally connected to the arm 19 of the feed-rocker 20 which is pivoted on the pintle-centers 21. The feedgq rocker 20 includes the upstanding arms 22 to which is pivoted at 23 the feed-bar 24 carrying the feed-dog 25 which operates upon the under side of the work through the usual slotted throat-plate 26 in which 1s formed the 25 needle-hole 27.

The pitman '18 has pivoted to it at 28 a slide-block 29 which enters a guideway 30 in the ide-block 31 pivoted at 32 to an internal iig 33 on the standard 2. A fingerao piece 34 is secured to the guide-block 31 and extends out through the vertical slot 35 in the plate 36 which covers the front openin 37 in the standard 2. Disposed immediate y behind the cover-plate 36 is the circularly ad- 23 just-able stop-plate 38 having several diderently spaced pairs of opposed stop-shoulders 39, 39 on dierent diameters of the stop-plate, as disclosed in the Hleb patent referred to.

The feed-bar 24 is forked at its forward end to embrace the roller 4() on the arm 41 of the feed-lift rocker 42 to which is Fixed the forked-arm 43 embracing the feed-lift cam 44 on the rock-shaft 45 which carries the usual forked arm 46 for oscillating the shuttle-driving shaft 47 through the usual slide block 48 and crank-arm 49 construction, disclosed for example in the patent to Diehl No. 374,661, of Dec. 13, 1887. The rock-shaft has an arm 50 which is connected hy the operating pitman 51 to the crank 52 on the main-shaft 7 When the nger-piece 34 is thrown downwardly, the guideway 30 in the block 31 is so inclined relative to the pitman 18 as to cause the feed-dog to move away from the operator when in its elevated position, thus glving a forward feedin movement to the work. When the finger ever 34 is thrown upwardly, the inclination of the guideway 30 is reversed and the pitman 13 is caused to move the feed-dog toward the operator when in its elevated position, thus giving a reverse feeding vmovement. to the work.

The shuttle-driving shaft 47 carries at its end remote from the standard 2 the arcuate thread-case arm 61 with the notch 62, Fig. 1,

in the usual rotation-restraining bar 63".

It will be observed that the shuttle oscillates in t. vertical plane parallel to the line of feed and that the shuttle is so constructed and arranged that its beak 58 seizes the nascent needle-loo 63, Figs. 2, 6EL and 7 on the side of the needle away from or more remote from the standard 2. It will also be observed that the beak of the shuttle moves in the direction of forward feed, or away from the operator, when seizin the nascent needle-loop.

The needle is t readed in a direction away from the standard 2, as shown in Fig. 1.

I have discovered that when the elements of the stitch-forming and feeding mechanisms are constructed and relatively arranged as herein disclosed, the machine will sew the desirable spirally formed orso-called perfeet stitch in either direction at the will of the operator.

Figs. 6, 6, and 6 show the formation of the stitch when the direction of feed is away l from the o erator. Here, the needle-loop 63 Fig. 6, is ing drawn up free from the objectionable half-hitch. So also in Fig. 7, with the feed reversed, the needle-loop 63 is hee from the objectionable half-hitch. ln both ses, looking in the direction of feed, the observer will see the needle-thread appreaching him in a clock-wise spiral around the bobbin-thread. A right-hand or clockwise spiralling of the needle-thread is desirable in sewing with the standard left-twist silk threads readily obtainable, as it tends to tighten the strands or ihres ot such threads. When the strands of a thread untwist or loosen while being stitched into the material, trouble is likely to be experienced with fraying or breaking oi the thre and furthermore the resultant senin is weakened and its ape pearance is unsatisfactory. As this action is more rononnced with silk than with cotton three. it has been the aim of sewing machine manufacturers to construct machines which will sew standard letttwist machine silk thread without raying or breaking such thread. v

Machines of the present type, as heretofore provided with a reversible feeding mechanism, were open to the objection that while they would sew a clock-wise spirally formed perfect stitch when ieeding the work away from the operator, they invariably formed a knotted or hitch-stitch of reverse twist when the direction of feed was reversed. As a result, such machines will tighten a left twisted needle-thread when feeding forwardly and will loosen the twistof the same needle-thread when feeding in the reverse direction. In fact such machines will. not ordinarily sew more than a few inches in the reverse direction with silk thread before/the thread is so frayed that it breaks.. This will be made clear by reference to Figs. 88L to 9? lnclusive. Here the shuttle 54 seizes the nascent needle-loop 63x11 on the side of the needle nearer the stand-n and the shuttle-beak passing between the needle and the lead of the bobbin-thread for either direction o'f feed.

In testimony whereofVv I have signed my name to this specification.

y MARTIN HEMLEB.

ard and consequently the needle 6'? is threaded `l0 from left to right, or toward the bracket-arm standard of the machine. The shuttle 54 carries the usual thread-case 60 havin the usual rotation-restraining tongue 61. en

f the feed is away from the operator, as shown 1B in Figs. 8, 8? and 8, the needle-loo 63 is cast about the bobbin in such a way t at it is drawn up, as shown at 63. Fig. 8,without a knot or hitch. When the direction of feed is reversed, however, as shown. in Figs. 9, 9b and 2o 9, there is an undesired and abnormal cooperation of the stitch-forming and feeding mechanisms which causes each needle-loop 63 Fig. 9, being drawn up to be half-hitched around the bobbin-thread as shown at 64.. A careful scrutiny of Figs. 9tz and 9 will make clear this objectionable condition.

It will be observed that the direction of twist of the needle-thread about the bobbinthread when feeding forwardly in the ma- 80 is right-handed or clock-wise, to favor the standard left-twist silk threads readily obtainable. When this machine is feeding rearwardly, however, (Figs. 9, 9" andv9) the direction of the spiral is reversed and the stitch also includes the objectionable hitch. The resultant seam is knotted and the strands of the needle-thread are loosened. The machine of the present improvement retains the desired clock-wise direction of twist and eliminates the hitch-stitch while feeding both forwardly and rearwardly.

It will also be observed that the open or accessible face of the shuttle of the present las and that the accessibility of the thread-case Vfor renewal of the lower thread-mass has not been impaired. y

Having thus set forth the nature of the invention, what I claim herein is In a sewing machine having a bed, a standard rising therefrom and van overhanging arm carried by said standard, the combination of reversible straightaway feedin mechanism, and stitch-'forming mechanism aving a reciprocating needle and an oscillating shuttle operating in a vertical plane parallel to the line of feed and passing bodily through a needle-loop, vthe shuttle having a beak arranged to seize the needle-thread loops on the sidel of the needle more remote from the standard, and a bobbin 'carried by said shuttle and accessible for removal from the I side of the line of feed more remote from said v standard, the lead of the bobbin-thread being across the open outer face of the shuttle lchine of the prior art (Figs. 8, 8b and 8)- machine is in the same position as heretofore,

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